The invention is related to an instrument for endoscopic surgery, comprising a casing, further comprising a sliding tube which extends into the casing with its proximal end and which is disposed longitudinally slidable with respect to the casing by means of an actuating mechanism, further comprising an electrode tube which extends through the sliding tube, which extends into the casing with its proximal end and is axially lockable therein, and further comprising two isolated wire pieces which extend through the inside of the electrode tube, the wire pieces comprising branches which protrude over the electrode tube and the sliding tube at their distal end, which are spread apart from one another slanted in opposite directions, which are elastically bendable with respect to each other in a radial direction against a spring force acting in the direction of spreading during a movement of the sliding tube, and which carry isolated bending sections and, at their free ends, metallic electrodes, and which wire pieces comprise contact elements which are electrically connected to the electrodes at the proximal end and which are adapted to be connected to a high frequency power supply.
Instruments for endoscopic surgery of this type are known (DE-A-43 37 590), which are suited to coagulate and dissect tissue, and which to this end have an exchangeable electrode tube which is rotatable within the casing, the branches of which electrode tube are fit ted, for example, with hook-shaped, parallel electrodes. This makes it possible to first load the biological tissue onto the concave side of the hooks and to lift it up, and to then coagulate or dissect the tissue. With the convex side of the hook-shaped electrodes it is possible to run along a portion of tissue in a curve and to thereby coagulate or dissect the tissue by evaporation. In the course of this process, the distance between the two electrodes may be adjusted as seen necessary. By opening and closing the hook-shaped electrodes it is possible to dissect bluntly with or without current.
In minimal invasive surgery it often occurs that tissue has to be dissected. When using the bipolar coagulation pliers, the dissection is effected by a heating process which leads to an evaporation of tissue. In this, it is found to be disadvantageous that smoke is created by the heating and that the tissue is cauterized. Scissors are therefore often used for the dissection, which cut the tissue mechanically. In this, there is the danger of bleeding, though. In order to stop the bleeding bi-polarly the instrument has to be changed or a further instrument for coagulation has to be introduced.